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Entity Framework 4 Code First - Prevent DB Drop/Create

开发者 https://www.devze.com 2023-03-08 15:39 出处:网络
I\'ve written an ASP.Net MVC 3 application using the Code First paradigm whereby when I make a change to the model the Entity Framework automatically attempts to re-create the underlying SQL Server Da

I've written an ASP.Net MVC 3 application using the Code First paradigm whereby when I make a change to the model the Entity Framework automatically attempts to re-create the underlying SQL Server Database via DROP and CREATE statements. The problem is the application is hosted on a 3rd party remote server which limits the number of databases I can have and does not seem to allow me to programmatically execute "CREATE DATABASE..." statements as I gather from this error message:

CREATE DATABASE permission denied in database 'master'.

Is there any way to stop the Entity Framework from dropping and attempting to re-create the whole database and instead make it simply drop the tables and re-create them?

After creating the database manually and running the application I also get the following error I guess as the Entity Framework tries to modify the database:

Model compatibility cannot be checked because the da开发者_如何学Ctabase does not contain model metadata. Ensure that IncludeMetadataConvention has been added to the DbModelBuilder conventions.


UPDATE: Found this gem through google, it sounds like its exactly what you need: http://nuget.org/Tags/IDatabaseInitializer

You can use a different database initializer. Lets say your context is called SampleContext then your constructor would look like this:

    public SampleContext() 
    {
        System.Data.Entity.Database.SetInitializer(new CreateDatabaseIfNotExists<SampleContext>()); 
    }

Note that the above is the default initializer. You will probably need to create your own custom initializer by implementing IDatabaseInitializer. Theres some good info here: http://sankarsan.wordpress.com/2010/10/14/entity-framework-ctp-4-0-database-initialization/


Using EF 4.3 with Migrations you do not get this behavior - at least I have not seen it. But I also have this set in my code -

public sealed class DbConfiguration : DbMigrationsConfiguration<DatabaseContext>
{
    public DbConfiguration()
    {
        AutomaticMigrationsEnabled = false;
    }
}
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